Upstream keepalive: comment added.

src/http/modules/ngx_http_upstream_keepalive_module.c

diff --git a/src/http/modules/ngx_http_upstream_keepalive_module.c b/src/http/modules/ngx_http_upstream_keepalive_module.c
index 90a226d..ef21ea2 100644
--- a/src/http/modules/ngx_http_upstream_keepalive_module.c
+++ b/src/http/modules/ngx_http_upstream_keepalive_module.c
@@ -518,6 +518,8 @@
 
     kcf->max_cached = n;
 
+    /* init upstream handler */
+
     uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
 
     kcf->original_init_upstream = uscf->peer.init_upstream